One of the differences is that one of the jumpers that is suppose to tell the cpu type to the motherboard is missing.

As you can see where the JP27 is suppose to be, there is no jumper.Another difference is that there is winbond chip where it says "real time clock" in the picture and there is a barrel battery next to the keyboard connector.

Baoran wrote:Quake benchmark works 3.8 fps no matter how I set the jumpers, so no idea what the jumpers actually do.

Perhaps it's just to set the correct CPU model at the BIOS POST screen?Does it change from SX to DX?Perhaps you could also try running some CPU info software from Norton or such, which try to determine the CPU type independently, and see if they change based on the jumpers?